Integration of ABE Solvents Fed-batch Biosynthesis with their Recovery by Gas-stripping

The biosynthesis of ABE (acetone, butanol, ethanol) solvents with Clostridium acetobutylicum occurs due to its growth in a glucose substrate medium. Clostridial ABE production is commonly conducted in bioreactors at a pH value of 4.5 and temperatures ranging between 36 and 38oC. Aiming at diminishing the butanol inhibitor effect on Clostridium acetobutylicum bacterial system, a controlled removal of solvents from reaction medium can be used for batch and fed-batch bioreactors. An experimental study of solvents removal by gas-stripping was performed in order to estimate the kinetics of solvents stripping from fermentation broth. A mathematical model was applied to solve an optimization case, i.e. to maximize the solvents production in a bioreactor which operates sequentially in batch, fed-batch, and fed-batch with gas-stripping system. An optimization function depending on the feed flow rate, substrate concentration in the reactor feed, switching time from batch to fed-batch system, and stripping start time was defined and evaluated.